A chainsaw is an automatic saw that is designed so that a saw chain formed in a chain shape is rotated by a driving source such as an electric motor or an engine to cut an object, and is widely used at a working site in the forest industry and the landscape industry. Since the saw chain is held by a guide bar, and is rotated in a state that the saw chain is in contact with the guide bar, and therefore, chain oil serving as lubricating oil used for reducing friction is supplied to the saw chain. As described in Patent Literature 1, a remaining amount of the chain oil can be visually checked by a worker through an observation window for checking the chain oil, which is provided in a housing of the chainsaw. The chainsaw is used outdoors in most cases, and therefore, the worker is forced to work in a dark location under a poor visibility in some cases depending on working environment and weather. In such a case, the worker sometimes hardly visually checks the remaining amount of the chain oil to be supplied to the saw chain, and therefore, sometimes illuminates the observation window with the light to check it.